Method for making GaN-based high electron mobility transistor

Abstract

A high electron mobility transistor including: a GaN material system based heterostructure; a passivating nitride layer over the heterostructure and defining a plurality of openings; and a plurality of electrical contacts for the heterostructure and formed through the openings.

1. A method for making a high electron mobility transistor comprising:
 providing a dielectric film over a GaN material system based heterostructure; 
 providing a photo resist mask over said dielectric film; 
 etching said dielectric film and heterostructure dependently upon said photo resist mask into a mesa structure; 
 removing said photo resist mask and remaining portions of said dielectric film; 
 low pressure chemical vapor depositing a dense passivating nitride layer onto the GaN material system based heterostructure, wherein the low pressure chemical vapor deposited passivating nitride layer is on the mesa structure, 
 etching openings in said nitride layer; and 
 forming electrodes in contact with the GaN material system based heterostructure and through said openings. 
 
     
     
       2. The method of  claim 1 , wherein said low pressure chemical vapor depositing comprises flowing NH 3  and SiH 2 Cl 2 . 
     
     
       3. The method of  claim 2 , wherein said NH 3  and SiH 2 Cl 2  are flowed at a ratio of about 7:3 sccm to form a dense nitride layer having a thickness of between about 450 and 2000 angstroms. 
     
     
       4. The method of  claim 2 , wherein said flowing is at a temperature less than about 800 degrees Celsius. 
     
     
       5. The method of  claim 1 , wherein said forming electrodes comprises metal evaporation. 
     
     
       6. The method of  claim 1 , wherein said etching openings comprises providing a photo resist mask over said dense nitride layer, reactive ion etching said dense nitride layer through said photo resist mask and inductive coupled plasma etching said heterostructure through said photo resist mask. 
     
     
       7. A method for making a high electron mobility transistor comprising:
 providing a dielectric film over a GaN material system based heterostructure; 
 providing a photo resist mask over said dielectric film; 
 etching said dielectric film dependently upon said photo resist mask to provide openings to said heterostructure; 
 plasma treating said heterostructure through said openings; 
 removing said photo resist mask and remaining portions of said dielectric film; 
 low pressure chemical vapor depositing a dense passivating nitride layer onto the GaN material system based heterostructure; 
 etching openings in said nitride layer; and 
 forming electrodes in contact with the GaN material system based heterostructure and through said openings. 
 
     
     
       8. The method of  claim 7 , wherein said plasma treating causes N-vacancies to be formed in said heterostructure. 
     
     
       9. The method of  claim 7 , further comprising prior to the low pressure chemical vapor depositing the passivating nitride layer:
 providing another dielectric film over the GaN material system based heterostructure; 
 providing another photo resist mask over said dielectric film; 
 etching said other dielectric film and heterostructure dependently upon said other photo resist mask into a mesa structure; and removing said other photo resist mask and remaining portions of said other dielectric film; 
 
       wherein the low pressure chemical vapor deposited passivating nitride layer is on the mesa structure. 
     
     
       10. The method of  claim 7 , wherein said low pressure chemical vapor depositing comprises flowing NH 3  and SiH 2 Cl 2 . 
     
     
       11. The method of  claim 10 , wherein said NH 3  and SiH 2 Cl 2  are flowed at a ratio of about 7:3 sccm to form a dense nitride layer having a thickness of between about 450 and 2000 angstroms. 
     
     
       12. The method of  claim 10 , wherein said flowing is at a temperature less than about 800 degrees Celsius. 
     
     
       13. The method of  claim 7 , wherein said forming electrodes comprises metal evaporation. 
     
     
       14. The method of  claim 7 , wherein said etching openings comprises providing a photo resist mask over said dense nitride layer, reactive ion etching said dense nitride layer through said photo resist mask and inductive coupled plasma etching said heterostructure through said photo resist mask.